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Full text of "Residue in the soil following atrazine applied as a preemergent and its effect on succeeding crops"

RESIDUE IN THE SOIL FOLLOWING 
ATRAZIN.E APPLIoD AS A PREEr^EROENT 
AND ITS EFFECT ON SUCCEEDliJCJ CROPS 



by 

JAMBS ERNEST COIJQROVE 
B. S., Kansas State University, 1962 



A MASTER'S THESIS 

submitted in partial fulfillment of the 

requirements for the degree 

MASTER OF SCIEi^CE 

Department of Agronomy 

KAMSAS STATE UNIVERSITY 
Manhattan, Kansas 

196i^ 

Approved by: 




<^Jl^yKi-<^ 



Kajor Professor 



uD 

TV 11 



ISTROIXJCTIOH 1 

B£VX£.W ^r i<lX£.rt4f UBB • I 

KATSRUZA AJD MBTEOOS 6 

EXFBBIMKMTAL RESULTS XO 

DlSCtJSSIO?! 31 

SUMKiRT 34 

ACn OVILS£]G > r T 35 

LITSIUTUHE CI? J 36 



INTRODUCTION 

The use of atrazlne as a preemergent for controlling annu- 
al weeds in com has created a problem involving the effect of 
residues on succeeding crops. Injury to susceptible crops fol- 
lowing corn treated with atrazine nas been observed. In ro- 
tations in which sensitive crops are included the use of atra- 
zine may become hazardous. 

The object of this investigation was to determine the 
effects of residues of atrazlne on crops commonly grown in 
Kansas. 

REVIEW OP LITSRATURE 

Atrazine is 2-chloro-i|.-ethyla>iino-6-isopropylamino-s-triazine. 
The "naterial is a white, crystalline substance which is sligntly 
soluble in water. The solubility of atrazlne has b«en found to 
be near 70 ppm at 27°C. (1) 

Atrazine has become well established as a selective pre- 
emergent herbicide for annual grass and broadleaf weed control 
in corn. 

Com plants are capable of metabolizing atrazine to prod- 
ucts which are not injurious. (1,11) Other crops showing sote 
tolerance are capable of metabolizing atrazine, but at a slower 
rate which per-^its the compound to accunulate to toxic levels, (1) 
Seeds of susceptible plants usually germinate but are killed 



shortly after emergence due to the uptake of atrazlne tiii*ough the 
roots. The first symptom of Injury Is marginal chloroais, (II4.) 
When applying atrazlne as a preemersient for weed control In com 
it has been found advisable to consider the effect of residues in 
the soil on succeeding crops, (ij.) 

Disappearance of herbicide residues from the soil involves 
a number of factors: vaporization, soil aasorption, leaching, 
chemical decomposition, photo-chemical decomposition, deacti- 
vation by nicroorganisms, removal by plants, and tillage. (3) 
Tiie above factors are influenced by the nature of the compound, 
physical and chemical properties of the soil, amount of rainfall 
and leaching velocity, temperature and amount of chemical ap- 
plied. (7) 

Rodgers (12) in his work with triazines found that atrazlne 
was Inactivated T.ore rapidly as temperatures increased to i|.5°C, 
He found that atrazine was inactivated in less than seven weeks 
during the summer but inactivation was markedly slowed when 
temperatures were below 30^0, 

Talbert and Fletcnall (20) applied two pounds of atrazlne 
and simazine per acre in May, I960. There was a rapid loss of 
the herbicide during the first three weeks after application. 
Rate of inactivation became slower through the summer and very 
little deactivation occurred during September and October. 

The amount of rainfall and leaching velocity are factors 
which are considered Important in loss of toxicity. iJue to the 
slight solubility of atrazine it is not leached rapidly: however, 



leaching has been found Important in dissipation when consider- 
ing an extended period of time. (6) 

Kuntz, et al . (9) found after applying two surface Inches of 
water Immediately after treatment that most of the atrazine 
remained in the top Inch of soil, i-'ollowlng an application of 16 
Inches of surface water after treatment, growth reduction of oata 
sown in the top inch of soil continued to occur* 

Bumslde, et al , (6) found that atrazine was leached to the 
12 to 13 inch soil depth after four ;nonths and to the li to 2i4. 
inch soil depth or greater after 16 months. A considerable amount 
of atrazine remained in the 3 to 2k Inch soil depth after 16 
months • 

Behrens (3) stated that considerable amounts of atrazine may 
be adsorbed In soils with a high organic matter content. He 
stated that recent evidence Indicates a deactivation of trlazlnes 
by polysulfldes or other electron rich compounds and that deacti- 
vation of atrazine by microorganisms is relatively slow. 

Sheets and Shaw (16) in their Investigation tested fourteen 
•-trlazlnes in four different soils. Atrazine was found to be 
the most toxic compound to oata in all four soils. The four 
soils were Tlfton loamy sand, 3a3icet sandy loam, Cecil sandy loam 
and Sharkley clay. Atrazine was rost toxic in Tlfton sandy loam 
and least toxic in Sharkley clay. 

Research with several crops concerning the effect of 
residues in the soil following applications of herbicides has 
been reported. 



Behrens (2) after applying 2, 6 and 12 pounds of atrazlne 
per acre in Kovernber, sowed flax, wheat, oats and planted soy- 
beans the following spring. Percentage kills were estimated. 
Wheat, oats and soybeans were completely killed following the 6 
and 12 pound rates while flax showed 73 and 33 percent reauctlons 
at 6 and 12 pounds respectively. The 2 pound rates severely 
reduced stands of wheat and oats but flax and soybeans were more 
tolerant. 

Buchholtz (5) reported severe Injury to oats on soil which 
had bean treated with atrazlne at 4 pounds per acre the previous 
year, Mo significant yield decrease was foxind with treatments 
of 1 and 2 pounds per acre. 

Pink and Pletchall (3) seeded nine different forages in soil 
treated one year previously with atrazlne at 1, 2 and I4. pounds 
per acre. The crops grown were orchardgrass, tall fescue, 
timothy, bromegrass, alfalfa, red clover, lespedeza, ladlno 
clover and sweet clover. They found no effect on emergence for 
any species but reported stand reduction after the 2 and 4 pound 
applications. Tall fescue was most susceptible while timothy was 
injured least. Significant yield reductions occurred with all 
crops following the 2 and l\. pound rates. The 1 pound per acre 
rate reduced stands for all crops except tall fescue and Korean 
lespedeza, 

Swader and Pletchall (19) substituted bluegrass for sweet 
clover in the above experiment. The 1 pound rate showed very 
little effect while the 2 pound rate caused considerable reduct- 



ion of stand In ladlno clover. The 4. pound rate caused r;evere 
reductions of stands In four species. 

Scballook and Ilnicki (13) reported injuiry to ryegrass when 
seeded in corn at last cultivation waen the com had been treated 
with atrazine as a preemergent. No injuiry was observed waen 
seeding was delayed until after corn iiarvest. 

Ilnicki and Keggitt (10) investigating residual aspects of 
triazine compounds made 1, 2, k» 6 and 3 pound per acre appli- 
cations of slmazine and atrazine. After initiating the experi- 
ment in 1959# the jrarre applications on the same plots were '^ade 
for three consecutive years. Rates of slmazine at I4. pounds and 
above caused injury to susceptible crops after one year. Hates 
of 6 to 3 pounds produced severe injury. Successive applicat- 
ions of 2 pounds for three years also produced severe injury. 
Results with atrazine were similar but less severe, 

Splittstoesser and Derscheld (13) reported severe Injury to 
S'^all grain when sown the year after application of 2 pounds per 
acre of atrazine, 

Sutaraarizing previous work with atrazine residues, results 
have shown vajpying degrees of tolerance arong different species 
of plants. Recommended rates of 2 to Ij. pounds have left residues 
injurious to susceptible species in some investigations. Loss of 
residues from the soil is dependent upon a number of factors 
which are variable. 



7iM InTeatlgatlan was conducted In 1963 <^t txM iiaxuiat 
3tftt« Univ6x>9itj AgroQonqr F»m» Maajriattaa, &aaa«a« Xb* soil 
b«liig ftn unna-i9d ••rlAS, i^leh I9 noarly lo^al, poorly dr«lae<jl» 
alluvlml sllty cla^ loa?B with a llj^t, sllty city eslcairoaufl 
•ubfoll,^ 

A flame cultivation taat to control v^tada In com was eon- 
ductad tn tha araa in 1962. Tan pounda par aora of atx*axlna %mui 
appllad 'ay 5» 1962 as a praarnargant to allmtnata any waad 
faotors in a -sor^lon of tha ai»«a ii9«d In tha fla^a tast. Tha 
raflMlnoar of tae araa ma not trf i j. m tiaa 1963 realdua In* 
vaatlgatton, tha two araaa mrw aoniparAd to datar-^lna tha affact 
of atraslna reaiduaa ra-talnlne- V^ tha soil* 

Total praolpltatloo In 1962 aftap tha atraslna was appllad 
waa naar normal, fhara waa a two waak dry parlod aftar t^ia atra- 
slna traat'^nt. A k^lk Inch rain on »^y 29 aooountad for oat 
of tha praalpltatton In May, storing tha ratnalndar of 1962, only 
ona rain of '^ora than 2 Inehaa fell, Praclpltatlon In 1963 waa 
balow nopf^l eaeh ""Onth raaultln^ in •xtre.'naly dry conditions 
during tha growing soason. Dally praclpltatlon fx^-v May I, 1962, 
through Sapta-ber 30, 1963, la Includad In table l, 

Tha araa waa plowad with a coldooaru plow to an approxi- 
mate dapth of Inchaa in tha fall of 1962. Tha soil waa laft In 



^Dr, 0, W, Uldwall, In paraonal •o«flMnlcatl:>a« 





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8 



this condition through the winter months. Prior to planting tb» 
various crops, the area was disced and harrowed. 

The area was divided into 21 equal plots, l\.0 Inches wide. 
The plots ran the entire length of the area. A random design 
with three replications was used in the experiment. Six crops 
occurring three times each, utilized 13 plots. The remaining 
three plots were not planted. The plots were in the aa.me 
sequence in both the treated and untreated areas. 

The crops were planted in two row plots with 1^0 inch spac- 
ings. One ifO inch quadrat for making weed counts was placed at 
random within each plot where a crop was not planted. 



Table 2^^ Crops seeded, variety, date of 
planting and date of harvest. 



Crop 



Variety jate of Planting Date of iiarvest 



Soybeans Clark 

Castorbeans Baker 

Poraf-e Sorghum Atlas 

Sudangrass Greenleaf 

Grain Sorghum Midland 

Sunflower Advance 



Hay 22 
Kay 21 
May 22 
May 22 
May 21 
May 29 



October 1? 
November 7 
September 9 
September 10 
September 9 
August 29 



\ 



Oats and alfalfa were seeded in the spring but no yields 
were obtained due to the extremely dry conditions at sowing tine 
which resulted in no alfalfa seedling survival and a poor stand 
of oats. 

The plots were kept weed free during the growing season by 
cultivation and hoeing. i^Jotes of observable injury were taken 
throughout the growing season. 



A 40 foot section of one row was imrvested from each plot. 
The above-ground portions of sunflower, forage sorghum and 
sudangrass were harvested, allowed to di^^, then weighed to 
measure yield. Soybean, grain sorghum and castorbean yields 
were deteirmined by veed weights. 

Weed counts in each quadrat were made and the above- 
ground portions of the weeds were harvested and weighed in 
August. 

To detect significant differences betwetn means of the two 
treatTients, the t-distribution for comparison of two randomized 
groups was utilized, iixperiraental error was determined by the 
average variation among the plots within the treatments. (1?) 

To determine the depth to which atrazine had leached, soil 
samples were obtained in May, 1963 and again in September. 
Samples were obtained with a one inch soil tube. Soil was taken 
from the to 6, 6 to 12, and 12 to 13 inch soil depths in June 
and from the same depths plus an 13 to 21j. inch depth In September. 
The samples were put in k inch pots and taken to the greenhouse 
where Kanota oats were grown as an indicator. The pots were 
watered daily by sprinkling. Atrazine injury to oats growing in 
the soil from various depths was observed. 

Soil samples from to 3, 3 to 6, and 6 to 9 inch soil 
depths were obtained in September, 1963 from the I963 flame cul- 
tivation test where 10 pounds per acre of atrazine had again 
been applied as a preemergent. Kanota oats were grown for a 
bloassay and injury resulting from atrazine residues at the 
different soil depths was observed. 



10 



On September 25» nodule counts were made on soybeans to 
determine if atrazlne residues affected nodulatlon. Twelve 
plants were selected from each replication in the treated area; 
four showing severe injury, four moderate Injury and the re- 
maining four plants having slight Injury. The mean number of 
nodules on the four plants was reported. Nodules on four plants 
from each replication in the check area were counted and the 
mean number reported. 

EXPERIMENTAL RESULTS 

Atrazlne residues resulted in early injury to sunflower, 
soybeans and castorbean. Marginal chlorosis was observed 
•hortly after emergence while overall Injury, in some Instances, 
was sufficiently severe to reduce the stand. Other plants were 
stunted throughout the growing season; however, some plants 
appeared to be uninjured. 

Yields gave indication that atrazlne residues reduced 
stand for the above mentioned species. Information concerning 
yield and stand of the above species are reported In the follow- 
ing tables. Calculated t values and the table t values obtained 
from Snedecor's Statistical Methods (1?) are included. 



SXflASATXQi OF i?tAS& I 

Cl«ner«l t1«w of •xperlnaot (lin«> 1963). 
Th» area to tha right %»• traatad with 
tan pounda par aera of atrasina in 1962, 



12 



PLATE I 



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EXPIANATION OP PIATH. II 



Caatorbeans wei*e severely Injured by soil 
residues. Weed growth in the treated and 
untreated quadrats was not significantly 
different. 



PLATE II 



14 




EXPIAUATION OP PIATE III 



Leaf chlorosis of young castorbean 
plants injured by atrazine residue. 



16 



PLATE III 







EXPIANATION OP PIATE IV 



Note reduced stand of soybeans. 
Forage sorghum and audangrass 
were uninjured by atrazine residue, 



PLATE IV 



18 




&&#iA2(ATI0li OF ^IAT£ V 



Mo •jpyartnt injury to fomg* or 
gmln •orghu'n or 8udAngrik«8» 



PLATE V 



20 







EJCPIANATION OP PIATE VI 



General view of experiment area, 
September, 1963» 



22 



PUTE VI 




EXPIANATION OF PIATE VII 



Oats oeedllnga In the center pots exhibit 
varying decrees of In.lury due to soil residue. 
The soil samples were taken in September, 1963. 



PLATE VII 



2k 




Table ^ 


Weight of sunflower plants in 


pounds per 


25 

40 foot row. 








Replication 










Untreated 
Treated 






1 2 
30.3 23.5 

0.0 10.3 






3 
17.6 
0.4 


% 

ZS.5 

D = 21.9^«^ 


Calculated 
Table l^ 


t = 
Se< 


4.20 
3d wej 


Table t : 2.73 
Lght of soybeans in pounds 


per 40 


foot row. 


Replication 


Untreated 
Treated 






1 2 
6.5 7.9 

4.1 4.3 






3 

2.8 


6.4 
ill 

D s 2.7-''- 


Calculated 
Table ^ 


t s 2.31 

Seed wei 
40 foot 


Table t =2.73 

Lght (not hulled) of 
row. 


castorbean in pounds per 


Replication 


Untreated 
Treated 






1 2 

15.3 14.3 
10.5 9.7 






3 
11.3 

3.4 


I 

14.0 

9fg, 


Calculated 


t = 3.46 Table t = 2.73 

•Isk denotes significance at , 
lignificance. 


.05 


level, n.a 


1. denotes 


l/^ster 

non a 





26 


Table 6. Nu^iiber of sunflower plants per 40 foot row. 




Replication 


1 2 3 

Untreated 54 74 62 
Treated 32 6 

D 


63.3 


Calculated t = 1.98 Table t z 2.73 




Table Jj. -^u^ber of soybean plants per 40 foot row. 




Replication 


1 2 3 

Untreated I60 146 134 
Treated 79 117 79 

D 


I 

146.7 


Calculated t = 3.77 Table t = 2.73 




Table 3. Number of castorbean plants per 40 foot row. 




Replication 


1 23 
Untreated 37 35 30 
Treated 19 ?l| 23 

D 


X 

34.0 

2if,7 

= 10.3"- 


Calculated t = 3.12 Table t : 2.73 




A t value greater than 2.73 Indicated a significant 




difference at the .05 level between means of the two treatTients, 


The yield difference between means of the untreated 


and 


treated sunflower plots was 21.9 pounds. The calculated 


t value 


of 4.20 was significant. Stand reduction was non significant 


with a calculated t of 1.93, Considerable variation among 



27 



replications reduced the value greatly. 

A yield difference of 2,7 pounds between means of the 
treatments with soybeans was also significant. The calculated 
t value was 2.31. Soybean siand was also reduced significantly 
by atrazine residues. The t value was calculated at 3»77» 

The calculated t value of 3.i+6 indicated a significant 
yield reduction of castorbeans in the treated plots. Stand re- 
duction was also significant with a calculated t of 3* 12. 

Data obtained from soybean nodule counts is presented in 
table ^. The figures appearing in the table indicate the mean 
number of nodules observed on four selected plants. As the 
table Indicates, there were twelve plants selected from each 
replication in the treated area and grouped into three classes 
of four according to degree of injury. Pour plants were 
selected from each replication In the untreated area. 

Table 9^. Mean number of nodules observed on four soybean 
plants, September 25« 



Replication 






1 2 

71 100 

1 6 
39 19 

72 53 


60 


77 

3 

25 
63 



Untreated 

Treated 

severely injured 
moderately injured 
slightly injured 



Forage sorghum, sudfluigrass, and grain sorghum gave no 
indication of injury during the growing season. Yields of the 
above species were not significantly reduced by atrazine 



28 



residues reniaining in the treated area. 

Information concerning yield of the above species is re- 
ported in the followinii tables. Calculated t values and th« 
table t values at the .05 level of significance are given. 

Table 10. Weight of sudangrasa In pounds per 1^0 foot row. 



Replication 



1 2 

Untreated 1^0.3 32.1 

Treated 39.6 32.6 



3 


X 


34.5 


35.6 


30.5 


2li.2 




D = 1.1+n.a, 



Calculated t = 0.33 Table t a 2.73 

Table 11. Weight of forage aorghUDia in pounds per k.0 foot row. 



Replication 


Untreated 
Treated 


I 2 

74.2 73.6 
71.0 79.0 


3 
71.3 
65.3 


X 

73.0 
71.? 

D Z l,ln.3. 



Calculated t Z 0.27 Table t : 2.73 



Table 12. Seed weight of grain sorghum in pounds par ij.0 foot 
row. 



Replication 

1 2 3 it 

Untreated 3.4 10,1 9.3 9.4 

Treated 11,0 9.1 9.1 9j2 

D = 0.3n.i 

Calculated t r 0.04 Table t = 2.73 



29 



Broadleaf and grassy weeds emerfjed In the treated area. 
Weed counts ^jade In the six quadrats placed at random in the 
two treatments showed no significant differences. Annual 
broadleaf weeds In the treated area appeared to be stunted 
during the early growing season. Rough pigweed, Arnaranthus 
retroflexus was the predominant annual broadleaf. Annual 
grassy weeds predominantly crabgrass, i>lRltarla sp and foxtail 
Setaria sp showed no injury In the treated area. 

The following tables Include information on weed counts 
made in the two treatments. Calculated t and table t values 
are included. 

"^^^l® ^^« itumber of annual broadleaf weeds per quadrat 
August 29. 



Replication 



Untreated 2t 25 15 20.7 

Treated 17 32 9 19,3 

^_.^_^^___^_^^^^^^^^^^^^^^^^^^^^^^ D : l.I|n.s. 



Calculated t r 0.19 Table t s 2.73 

Table lii. Number of annual grassy weeds per quadrat August 29, 



Replication 



1 2 3 JS 

Untreated 15 . 13 l5 Ik, 3 

Treated 21 2 9 10, 



D = 



4 

• on. 2 



Calculated t = O.64 Table t s 2.73 



30 



Calculated t values Indicated that atrazine residues did not 
reduce broadleaf or grassy weed stand significantly. 

Table 15 « Weight of annual weeds per quaarat August 29. 



iieplicatiou 



12 3 it 

Untreated 34. 1 22.2 22.3 26.L. 

Treated 27.9 13.9 17.4 21.k 



D s "T70n.s. 



Calculated t Z 1.00 Table t z 2#73 

The weight of annual weeds was less in all replications for 
the treated area but the difference In means between treatments 
was not significant at the .05 level. 

Injury to Kanota oats grown on soil obtained from various 
soil depths in June, 1963 indicated atrazine residues concen- 
trated at the 6 to 12 inch soil depth. Slight injury to oats 
grown on soil collected from the to 6 and 12 to 13 inch depth 
was observed. Oats growing in soil frojn the 6 to 12 Inches 
were killed by atrazine residues. 

Soil obtained in September, 1963 from the 12 to 13 inch 
soil depth contained the highest concentration of atrazine at 
that date as indicated by severe injury to Kanota oats. Oats 
growing in soil collected from to 12 and from the 13 to 2l|. 
inch depths were only slightly Injured by atrazine residues. 



3X 



DISCUSSION 

Previous investigations of atrazine soil residues have indi- 
cated toxicity to susceptible crops following rates of 2 to 4 
pounds per acre. Rates of 3 to 12 pounds per acre applied the 
previous year resulted in near complete kill of r^any crops. 
Based on this information the 10 pound rate used in this in- 
vestigation was expected to cause considerable injury to the 
susceptible crops included. 

Based on the results of this investigation it appears that 
monocotyledon crops are more tolerant than dicotyledons; how- 
ever, in some cases certain broadleafs have been found to be 
more tolerant. 

Although significant reductions in yield were found in soy- 
beans, castorbean and sunflower, the yields were higher than 
anticipated in each crop. A number of factors may have been 
responsible for the relatively low toxicity of the atrazine 
residues in this investigation. 

Following the atrazine application May 5» 1962, there was a 
period of two weeks before i?ain fell. Without moisture to leach 
it into the soil, considerable atrazine may have be«n lost 
through volatilization or photo-chemical decomposition. 

Soil sapiples were not obtained in 1962 hence the depth of 
leaching at plowing time was not known. Since most of the rain- 
fall came as lignt showers and with a soil of relatively high 
clay content, it is assumed that leaching may have been slow 



32 



with most of the atrazlne reiialnlng near the surface. In- 
verting the soil by plowing to a depth of 9 Inches obviously 
placed the residues at a greater depth from the surface. Pre- 
cipitation through the winter months was below normal and leach- 
ing was probably retarded. From time of application to time of 
plowing only 5 rains of rrore than one Inch fell, while during 
the 3 tronths from October 1 through May 31 only 10, l5 Inches of 
precipitation fell, including 2 rains more than one inch 
(table 2). 

Oats grown in the greenhouse on soil obtained from various 
depths in the spring indicated atrazlne residues were concen- 
trated at the 6 to 12 inch depth which would verify the assump- 
tion that plowing placed the atrazlne in that zone of the profile. 

Loss of toxicity through soil adsorption, cheniical decom- 
position and deactivation by soil microorganisms was not mea- 
sured. It is known, however, that soils having a high clay 
content reduce toxicity of atrazlne through adsorption, (3,16) 
One investigator (3) stated that decomposition of atrazlne by 
microorganisms is slow. The amount of chemical decomposition 
which is influenced by chemical constituents of the soil may 
have been considerable in this investigation. 

The soybean nodule counts Indicate an indirect effect of 
atrazlne on nodulatlon. It appears that nodulation is reduced 
due to the reduction of vigor in the soybean plant, i^lrect 
toxic effect of atrazlne to the bacteria Involved is unlikely. 

Conclusions concerning loss of toxicity from residues are 



33 



difficult to postulate from Information obtained in this in- 
vestigation. Since plants becone rove tolerant to atrazine as 
they grow, the fact ttiat atrazine was located some depth from 
the surface nay have been the primary reason why some plants 
of the susceptible crops were able to grow. Because tae atra- 
zine was at that depth, the plants were able to become establis- 
hed as seedlings and to grow for a period of time before being 
subjected to atrazine residues. 

Based on results of this investigation, it appears that 
the varieties of forage sorghum, grain sorghum and sudangrass in 
this study can be grown following corn treated with atrazine. 
With experiment, other varieties of these same crops may be less 
tolerant. However, conditions differing from those in this ex- 
periment could result in significant reduction of yield. 

The varieties of castortaean, soybean or sunflower in- 
cluded in this experiment were susceptible to atrazine. Growing 
these varieties following atrazine application should be avoided. 
Other varieties .nay have more tolerance. 

Additional Investigations concerning the effects of various 
soil and climatic factors and also cultural practices on atrazine 
residues need to be conducted. Tolerance to atrazine of various 
varieties of different species would be valuable Infor.-nation to 
the far-ner. 



34 



Baaed on experimental results it was found that 
residues fro-^ ten pounds per acre of atrazine applied the 
previous year caused the following i 

1. Injury to young plants of soybeans, 
castorbean and sunflower. 

2. Yields of soybeans, castorbean and 
sunflower were reduced significantly. Yields 
of forage sorghum, grain sorghum and sudan- 
grass were not affected. 

3« ^ewer nodules were observed on soy- 
bean plants injured by atrazine residues. This 
was believed due to reduction of vigor of soybean 
plants. 

4. Annual weed population was not reduced 
■Ignificantly, 

5. Hesidues were concentrated at the 6 to 
12 inch depth in June, 1963 and at the 12 to 13 
inch depth the following September. 



35 



ACOOWLEOaMENT 

The author would like to express hia sincere ap- 
preciation and thanks to his major advisor. Dr. L, E, 
Anderson, for suggesting the problem, his guidance through- 
out this Investigation and for his critical reading and 
correction of the manuscript. 



36 



(1) 



LITEHATU-^ (jXTED 



Atrazlne Technical Bulletin no. 63~1 . 
Gelgy Agricultural Cherrlcals. Yonk 



Igy Agricultural Cherrlcals. Yonkers, New York. 1963. 



(2) Behrens, R, 

Relative residual phytotoxlcity of aimazlae and 2-chloro- 
l4.-ethylamlno-6-laopropylarnlno-3-trlazine (atrazine) , 
Proc. NCWCC and WCV/CG 16:103. 1959. 

(3) Behrena, --i. 

Soil residues from herbicides. Ag, chemicals 17:31|. 1962. 

(J^.) Buciinoltz, K. P. 

Avoid those herbicide residues. Crops and Soils 15; 15-16. 
April 1963. 

(5) Buchholtz, K. P. 

i?03?onses of oats to residual triazine herbicides in the 
soil. Proc, NCWCC and WCWCC 16:3?. 1959. 

(6) Bumside, 0. C, C. H. Fenater and Ci. H. Wicks. 

Dissipation and leaching of aonuron, sitnazine and atrazine 
in Nebraska soils. Weeds 11:209-213. 1963, 

(7) Burschell, Peter and V. H. Freed. 

The decomposition of herbicides in soils. Weeds 7: 
157-161, 1959. 

(3) Pink, Rodney J. and 0, H, Pletchall, 

Porage crop establishment in soil containing atrazine or 
slmazine residues. Weeds 11:31-33. 1963. 

(9) Kuntz, J. E., T. T. Kozlowski and R. R. Kilbury. 

Loacliability, movement and persistence of herbicides in 
forest nursery soils. Proc, NCWCC 17:12. I960. 

(10) Ilnicki, Richard D. and Willian P. Mep.gltt. 

Some residual aspects in the use of triazine compounds 
for weed control. Abstracts WSA:i4.6-l|7. I96I. 

(11) Montgomery, Marvin and V, fl. Freed. 

The uptake, translocation, and metabolism of sitnazine and 
atrazine by corn plants. Weeds 9:231-237. 1961. 

(12) Rodger s. Earl G. 

Leacaing of four triazines in tliree soils as influenced 
by varying frequencies and rates of simulated rainfall. 
Abstracts Proc. SWG:263. 1962. 



37 



(13) Schallock, D, A. and R. D. Ilnlcki, 

Herbicides: an effective weed control tool that rpust 
be used skillfully to prevent soil residue buildup. 
American Veg. Grower 10:20. 1962. 

(14) Schneider, E. 0, 

Slmazlne and related trlazlne herbicides, Proo. NCWCC 
15:11-12. 1953. 

(15) Sheets, T. J., A.. S, Crafts and H. Drewer. 

Influence of soil properties on the phytotoxicitles of 
the a-triazlne herbicides. Jour, Agr. and Pood Ghea 
10;i4.53-ii.62. 1962. 

(16) Sheets, T, J. and W, C. Shaw, 

xierbicidal properties and persistence In soils of 
s-trlazlnes. Weeds 11:15-21. 1963. 

(17) Snedecor, Cieorge W. 

Statistical i-iethods, Fifth Edition. Iowa State Univer- 
sity Press, Ames, Iowa. 35-92. 1956. 

(13) Splittstoosser, W. E. and L. A. Derscheid. 

Effects of environment upon herbicides applied preem- 
argence. Weeds 10:3014.-30?. 1962. 

(19) Swader, J. a. and 0. H. Fletchall, 

Effect of several herbicide residues on the establishment 
of certain forage crops, Proc. NCWCC 19:129-130. 1962. 

(20) Talbert, Ronald E. and 0, H. Fletchall, 

Hate of Inactlvatlon of atrazlne and siraazine in field 
plots as determined by bioaaaay techniques. Abstracts 
WSA:5. 1961, 



RESIDUE IN THE SOIL FOLLOWING 
ATRAZINE APPLIED AS A PEtEE?<BRGENT 
AND ITS EFFECT ON SUCC SEEDING CROPS 



by 

JAKES ERNEST CON GROVE 
B. S,, Kansas State University, 1962 



AJT ABSTRACT OP A MSTiCR'S THESIS 

submitted in partial fulfillment of tb« 

requirements for the degree 

MASTER OP SCIENCE 

Department of Agronomy 

KAN SAS STATE XS'd IVERS ITY 
Manhattsm, Kansas 

1964 

Approved byj 



Major Professor 



Injury to sensitive crops has been noted when planted 
In areas treated with atrazine the preceedlng year. Previous 
Investigators have found varying degrees of Injury from 
atrazine residues under different climatic and soil condit- 
ions and with differing cultu]?al practices employed. Anong 
species of plants, a considerable range In degree of tol- 
erance to atrazine is found, 

A field study was conducted In 1963 to deter'r,lne the 
effect of atrazine residues to crops which are grown in 
Kansas. In 1962, ten pounds per acre had been applied to 
provide a weed free area as part of a flame cultivation 
experiment with com. 

The crops grown Included soybeans, sunflower, castor- 
bean, gi?aln sorghum, forage sorghum and sudangrass. They 
were planted in two row plots occurring at random, with 
three replications In both the treated and check areas. A 
t test was used to detect significant differences between 
the two treatraents* 

Young plants of castorbean, sunflower and soybeans showed 
signs of injury the year following atrazine application. 
No injury was noted in forage aorghura, grain sorghum or 
sudangrass. Yield reduction was significant in castorbean, 
sunflower and soybeans but not apparent in forage sorghum, 
grain sorghum or sudangrass. 

Weed counts made in August frorn quadrats placed at 
rando'^ indicated atrazine residues did not reduce the annual 



broadleaf or grassy weed population significantly. 

Fewer nodules were observed on soybean plants showing 
atrazlne injury. This was believed due to reduction of 
vigor of soybean plants and not to direct toxic effect of 
the residues to the bacteria involved. 

In a bioassay test, Kanota oats grown In soil samples 
obtained from various depths indicated atrazlne residues 
were concentrated at the 6 to 12 inch depth in June, 1963, 
and at the 12 to 13 inch depth in September. 

Under the conditions of this experiment, toxic residues 
were dissipated more rapidly ttian anticipated. Absence of 
rainfall for two weeks following application, lack of 
leaching rains during the summer of 1962, a i»elatively high 
clay content of the soil In addition to the fall plowing 
operation are believed to be conducive to these results.